High-tension telephone system



F. C. DOBLE. HIGH TENSION TELEPHONE SYSTEM.

APPLiCATION fILED JULY 30.1919.

Patented A110. 24, 1920.

UNITED STATES FRANK C. DOBLE, OF TNINCHESTER, I'Y'IASSACEUSETTS.

HIGH-TENSION TELEEHONE SYSTEM.

Application filed July 30, 1919.

'o (all cli/icm it muy cono/ira:

Be it known that l, Fna-.Nn C. DOBLE, a citizen ci' the United States, residing at Yinchester, in the county et Middlesex and State liassacl Lisetts, have invented new and useful Improvements in High-Tension rl`elephone Systems, of which the following is a speciiication.

rllhe present invention has reference to telephone systems arranged in parallel with high tension electric transmission lines. rlelephone sysgems so provided are generally the private lines oit companies operating high tension power lines, and they are almost universally strung upon the towers which carry the line wires of the power system, on account of the obvious advantages of economy in equipment, maintenance and protection. The protection afforded by this manner ot running the telephone line includes both protection from lightning, for the telephone line is screened by the transmission line and the protections ot that lino against the effects ot lightning, and from theft ot wire and malicious damage. How over, telephone lines so carried, and also any lines running parallel and near to transmission lines, are charged with high potential, even under conditions or normal operation of the power transmission lines, while they are additionally subject to great disturbances under abnormal conditions, such as switching over the transmission line, arcing grounds, lightning disturbances, etc., which cause by their inductive elifect surges of extremely high volta-ge in the telephone lines.

lleretoiore, the telephone systems arranged and used as above indicated, have been low tension systems, which are intended to be so arranged that no other part of the system than the circuit or line wires can maintain high tension conditions. Any low tension system is very difiicult to maintain, even under the best normal operating; conditions of the adjacent high tensionI transmission line, while any of the abnormal conditions such asthose above mentioned not only'r'ender the telephone system dangcrousto the operators, but may also destroy the apparatus. I

It is the purpose of the present invention, which l desire to protect herein, to iiurnish. a high tension telephone system, in which all parts, including not only the circuit line but also the instruments, are capable of Specification of Letters Patent,

i ion, th

Patented Aug. 24, 1920.

Serial No. 314,365.

maintaining a high voltage with respect to the earth potential, and of being operated safely and with satisfactory results in the intelligible transmission ot' speech, under practically all conditions, and, in any event, under many of the conditions which render a low tension system inoperative, or even destroy i The principles or" the invention, and the manne in which at present I put them into eii'ect, are disclosed in the following specification, and pointed out in the appended claims, in connection with the drawing referred to in said specication.

' In this drawing:

Figure l is a diagram oit a high tension telephone system embodying my invention, including, for illustration, a central station, and two local stations.

Figs. 2 and 3 are respectively a iront and a side elevation ot a telephone instrument containing some ot the means which l have provided as part of the invention, for protecting the operator from harm from e3:- cessive potentials in the system.

"l i is an elevation, as seen from the c 2, o' the protection which guards o receiver hook. he saine protection is own in 2, as a section taken on line d ig. 4.

etere ce characters indicate like in all of the ligures. fc/,mi o1is-lf`i7lieretfer in this speciiicae following words are used as referring t the high tension telephone system in which the present invention is embodied, they are to be understood as having the tollowing meanings 1- Circuit is understood to mean an arrangement oi wires connecting two or more points between which communication is desired.`

Instrument 7 is understood to mean apparatus arranged for transmitting and receiving electricalv impulses over the circuits in manner which reproduces sounds or signals, and most particularly the sounds otarticulate speech.

Station is understood to mean a booth or platform, to which the instruments are, or may be, attacher, and which is occupied by the operator when using the tcm.

Protection is understood to mean a combina ot appar us which sate rirds the operator anc parts of the system JJ lett from excessive potentials and dangerous electrical disturbances. Y

System 7 is understood to mean a combination of circuits, instruments, stations and protection which as a whole Ypermits operators to communicate safely.

Operator is understood to mean a per-v oi'ice, or the despatchers oliice oi the power transmission line, or it may be any other station where two or more telephone lines enter, and trom which communication may be had with local stations, or by which local stationsv may be connectedV for communication one with another. Station B and ""station" C represent two o'f the local stations inthe system to illustrate the principle ot the invention. ln each local station, a represents a booth, which may be an inclosed chamber, or simply a supportof any suitable character to mount the telephone instrument b, having a platform or ioor c, on which the operator may stand.

eZ, e, and cZ, e represent the line wires ot the system between the local stations and the central station respectively.' lt is to be understood lthat these line wires may be strung on the towers of a high tension power line, or on separate poles, in any approved way, and secured by any approved means, fit shown diagrammatically, for illustration,l an insulator arranged 'to support one of thel wires. .it may be understood, without further illustration or statement, that this insulator represents one oiE the tele.- phone wire supporting insulators on one of the towers or poles, and that all of the lines may be supported by like or equivalent insulators. y

The branch connections from the line wires oi the circuits to the respective instru- Ynient-s are substantially alike in all cases,

land all such connections necessary for the stationsv represented in the diagram are shown in Fig. 1 in parallel, with the corresponding elements of the protection in the several branches beside one` another, and

designated byproper legends. The branch connections leading to all the instruments are designated by the same reference letters, g andl zr respectively. A horn gap is provided to .ground from eachl side of the branch connection, to drain of? surges ofthe highest potential in the circuit. Disconnect switches are located in both sides of the branch, andare intended to be normally closed. V@n the station side ot the disconnect Y ground. Thisiinsulation saeguarcs tl f branch, and horn gaps from each side ot the branch to earth, The purpose of these choke coils is well known and understood; that ot the horn gaps is to discharge excessively high potentiahvand that of the cylinder gap and vacuum arrester to equalize the potential in both sides of the. branch, whereby to obtain the balance necessary tor avoidance ot objectionable sounds in the instrument. ln this description, the term branch intended to mean the wires which run to the instrument from the line, whether such wires are in fact the ends of the line wires at a terminal station orv shuntr wires cut into the line at intermediate points. In other words, the wires running to any instrument in the system are considered as a branch within this definition.

rThe booth is highly insulated from the ground by .ieans of insulated supports y', j.

1t is also preferably raised to such a high elevation above the ground that it cannot be entered except by the person entering it lirst stepping upon a step 7o, at a lower elevation, but also 'insulated from the ground by insulated supports Z, Z; this step, oi course, being likewise ot such wide dimensions in each direction that operator in the booth can not even reach over and mal-:e contact with a person standing on the erator from ground, not only by making impossible to speak into the instrumem` whileV standing on the ground, but also by preventing a casual and accidental contact, which might occur through handing something to a'personstanding on the ground.

Further 'protection from ground, provided on the instrument itself, is s own particularly in Figs. 2, 3 and 4, and consists of a non-conducting boi m, inclosing the local circuit' and connections ot the instrument, a'case a on the front of the box, inclosing a transmitter and leaving only the non-conducting mouthpiece exposed; guard 0, 'overhanging and surrounding the hook p on which the receiver Q is support il when not in use, in the usual'manneryand insulating protection L'iter the crank or' the magneto in the signaling circuit. he lastnamed protection consists ot' disks r and s of, insulating material, inclosing the crank onl the Ymagneto or motor, and a handle t, likewise of insulating material, secured to said'disks.Y Y l The central station is protected by essensuch means including the insulated platform c and insulated step 7s, and protections for the instrument. In the diagram there is indicated in connectioniwith'the central sta- Ytially the 'same means as the local stations,

tion means by which the instrument of that station may beV connected with any orn 'the local station instruments, and by which any of the local stations may be connected with one another. rFliese means comprise Vtwo pairs et bus bars, l, 2 and lb, 2b, having contacts tor double-throw switches, which are connected with the central station instrument and with the several circuits respectively. The locations of these doublethrow switches are designate-:l at 1,2, 3 and lt is intended by this illustration to indicate that any number of circuits be brought into the central s ation, with provisions `for coupling them, described. Y

To complete the disclosure oi? protection, l have also shown in the diagram means to insulate a ponerl ringing device at the eentral station i'rom ground. rEhe ringing device comprises a generator l0, connected in the ringing circuit, in which there is a switch, controlled the operator and indicated at 13, and an electric motor ll, niechanically connected to the generatoi` by shaft l2. The generator, ringing circuit and switch are protected by t ie insul. tion ot the operators station, but the motor is not so protected and may be connected in any power circuit which is not protected, or may not be protected, against discharge of such high potentials as may be imposed on the telephone system. Hence the motor is considered as ground with respect to my system, and the safeguard or protection against discharge to ground at this point is atlorded by making the power shalt l2 liliewise an insulator or. suliiciently high resistance to prevent discharge. lllaterials suitable Yfor an element ot this sort, which is at the same time a power transmission means and an insulator, are wood,"hard liber and various other known materials. i

Briefly summarizing the features oli the invention which l have just described at length, the system consists o" First A very carefully'cons ructed and iighly insulated circuit, all partsot the circuit being supported byinsulators of such high resistance as to prevent short circuiting by the highestvoltages liable to be irnposed on the telephone system.

Second. Instruments which are preferably connected directly to the circuit, and have all metallic connections or terminals insulated against possible contact with the operator. rThis feature ot the direct connection between the instrument and the circuit y is highly important because it greatly augpotential between parts ot the system, and

offers only a very high resistance path to the ground, which relieves the system of abnormally high potentials. The protection here referred to includes the horn gaps, choke coils, cylinder gap and vacuum arrester previously described, TWhile the horn gaps permit discharge to ground, they are nevertheless of such high resistance lthat they permit discharge only ot excessively high charges, and no attempt is made to bring the potential iu the circuit at all near `Ahe earth potential. The cylinder gap and vacuum arrester merely equalize potential in the circuit on opposite sides oi the instrument, to secure the balance essential to obtaining a quiet line.

l have found by experience that, as a result of the novel characteristics previously described and above summarised,l a telephone systeiu is obtained, which is not liable to destruction or even derangement by abnormal conditions encountered in high tension transmission service, over which conversation can be carried on, even when such abnormal conditions exist, in practically all es except, possibly, at and immediately atter a stroke of lightning, and in the use olf Awhich the operators are safeguarded. The

'system would be altogethe useless.

'lhe system thus described is operative under all the conditions in which any low tension telephone systemv is operative, and also under conditions where, lor example, the induced pressure on the system is of an order olf magnitude of thousands of volts, conditions in which the low tension system may not be operative at all. *When there is no voltage in the power line, there is no appreciable impediment to transmission of speech in the telephone system., on account of the fact that the instruments are directly connected to the line without intermediate transtorniers or drainage coils. It is thus made possible by my invention to communicate over the teleplio-neline at any and all times, except at the instant of actual lightning str. or similar disturbance: while the danger to the operators reduced to the minimum and is much less than with other systems when operating under like conditions oiz disturbance.

"Wh at claim ind desire to secure by Letters Patent is:

l. [i .high tension telephone system having all its parts insulatedAv from ground and'so designed -thatx nopartofthe system Will break down' to ground under a sustained electricalstressless than one thousand volts pressure (rootmean square sine Wave value)` Y atl any frequency; and comprising Vas such partsa circuit,-a telephone instrument and an foperator-sf station.

2. A' high tension telephone system, comprisinga circuitradapted to run in proximity to an electric powerV transmission line, and havingmeans` for substantially equalizing the potential in allparts thereof, a telephone instrument in direct connection with sait circuit, and high yresistance 'insulating means adapted to sustain an electricalstress up to one thousand volt's- (root mean square sine.

v direct connection Withfrthe Wires 0f said branch circuit, air'lgaps between the wires of said branchcircuit andthe groundto discharge excessively high potential in the circuit, means tov-equalize t'hepotential in both sides ofy the branch, andan operators station, allsaid' parts being insulated from the ground to withstand breaking down under a sustained electrical stress ofy one "thousand volts (root meansquare sinewave value).-

5. In ahigh tension telephone systeman operators station comprising aplatform,

Vhighf resistance insulation supporting said platform, an instrument at such afheight above'said platform thatan operator in using itis compelled to occupy'the platform, and an approachfvstep to the platform also insulated `from .the ground and being arranged to serve as a guard preventing contact between an-operatorusing'the telephone and a person on the ground; ,A

6. Ina high tension telephone system, a telephone instrument having the usual receiver hook for supporting the receiver, a transmitter,.andsuitable circuits, and comprising also insulating material inclosing all metallic parts ofthe instrument.

LA high tension telephone system, comprising a.v circuit adjacent to an electric power -transmission line, means for grounding surges ofexcessively high potential in said-system While maintaining the potential of the system relatively high above `the earthpotential, means for qequalizing the potential. inthe circuit, a telephone instrument directly Vconnected Vto the circuit, insulating meansinfconnection With said instrument, arranged to guard' the metallic parts thereof from contact With an operator using the instrument,.and`a raised and highly insulated'platform for the operator.Y

8: AA high tension telephonesystem, comprisingv aA circuit- Vadjacent to an electric power transmission line, means for grounding surges ofI excessively high potential in said ,system WhileV maintaining the potential f= thc system relatively high above the earth potential, means forvequalizing the potential inthe circuit, a telephone instrument directly connected yto the circuit, insulating means innconnection with said` instrument, arrangedto guard all'metallic parts thereof from contact withA an operator using the instrument, a raised and'highly insulated platformforthe operator, and a guard preventing contact between an operator using the instrument and a person standing on the ground.:

.FRANK c. DOBLE. 

